Rheostat



(No Model.) 2 SheetsSheet 1.

F. 0. BLAGKWELL.

RHEOSTAT. No. 467,078. Patented Jan. 12, 1892.

WITNESSES: INVENTOR:

I Ivar ATTYS.

(No Model.) 2 Sheets-Sheet 2.

P. O. BLAGKWELL.

RHEOSTAT. No, 467,078. Patented Jan. 12,1892.

WITNESSES: INVENTOR:

15 a as W W w.

ATTYS.

I imiter) STATES PATENT OFFICE.

FRANCIS O. BLAOKWELL, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THETHOMSON-HOUSTON ELECTRIC COMPANY, OF CONNECTICUT.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 467,078, dated January12, 1892.

Original application filedJ'une 5, 1889, Serial No. 313,180. Divided andthis application filed January 1-2, 1891. Serial No. 377,539.

' (No model.)

To all whom, it may concern.-

Be it known that I. FRANCIS 0. BLACK- WELL, a citizen of the UnitedStates, residing at Boston, county of Suffolk, and State ofMassachusetts, have invented a certain new and useful Improvement inResistances for the Regulation of Electric Motors, of which thefollowing is a specification, this application being a division of myapplication for electric-motor regulation, Serial No. 313,180, filedJune 5, 1889.

My invention relates to a resistance-box and resistance for theregulation of electric motors, and particularlythose which are used forpropelling cars upon an electric railway.

It belongs to that class of resistances which consists of a series ofmetal plates set edgewlse and cut into and out of circuit by a travelingcontact.

The specific points of novelty are hereinafter pointed out in theclaims, and for an understanding of them reference is made to theaccompanying drawings, wherein- Figure 1 is a diagram of a motor andresistance connections. Fig. 2 is a side view of the resistance-box andtraveling contact. Fig. 3 is a plan view of the same. Fig. 4 isa detailsectional View of the box holding the resistance plates and box, andFigs. 5 and 6 are views showing a convenient form of mechanism forthrowing the resistance into and out of circuit when the same is used onan electric car.

The improvements forming the subject of this application have beenalready illustrated and described in connection with certain otherimprovements in motor-regulation in my application, Serial No. 813,180,filed June 5, 1880. As therein pointed out, it has been found that whencutting out field-magnet coils an extra currentis induced which tends toinjure the insulation. To avoid this Iprovide a resistance which can becut into and out of the main line to vary the resistance of themotor-circuit as a whole, and a secondary resistance through which thefield-magnet coils may be gradually cut out. Thisis illustrated in Fig.1, in which-- A represents a motor having the two limbs of thefield-magnet coils in series with the armature, but in multiple arc withone another. 0 is a resistance adapted to beinserted in series with themotor by means of the lever D. As the lever D is moved from the full tothe dotted line position it varies the resistance of comprises main andsecondary resistances corresponding to the two portions 0 C in thediagram Fig. 1.

Other features of construction are well adapted for the regulation ofmotors generally, and in claiming them I should not be understood aslimiting myself to a particular system of regulation only, such as seenin c the diagram.

The resistance preferably consists of thin iron plates set edgewise in abox in superfi cial contact and provided with contact-rollers adapted topass over the plates; butinstead of making one large long pile of theplates I arrange them in separate series or rows, each contained in anindependent box E, complete in itself and insulated from thesupportingframe D. The plates are insulated from the box by means offire-proof insulation, such as mica or asbestus. plates are placed sideby side, arranged in pairs, and a series of contactrollers are adaptedto travel over them. These contactrollers F are fastened in pairs to aninsulating-traveler G, which is adapted to move over the boxes on guidesH, the rollers of each pair being electrically connected through a metalbracket F from which they are hung, or other suitable means. The rows ofplates then being considered as arranged in pairs, the individual rowsof each pair are connected electrically by rollers F and the pairsthemselves in series by a wire or wires K. It will thus be seen that asthe piece G with the rollers attached moves over the boxes of plates 100The boxes E and rows of more or less of the plates will be brought intoseries and the resistance of the circuit thcreby controlled. At onepoint in the series of resistance-plates blocks of insulating material Iwill be inserted. These blocks will be similar to the end blocks I,which are made of slate or similar non-combustible material, so that thecircuit may be interrupted upon them without damage.

As will be seen in Fig. 4, the box E is open completely at its uppersurface to permit the rollers to pass over the edges of the plates andhas a similar narrower opening at the bottom. This allows a circulationof air without interruption from the contact device, while at the sametime it affords a corner or ledge S for holding the plates. Theelectrical connections with the plates are preferably made from thebottom, as seen in Fig. 2, where the binding-posts K are attached tocertain plates of the series and extend outward through the opening inthe bottom of the box. The contact device therefor does not interferewith the flexible connections which lead from the binding-posts to themotors upon the truck and other parts of the vehicle. The electricalconnections with the plates of the resistance correspond with thediagram in Fig. 1. The main resistance 0 of the diagram corresponds tothe larger box of plates. The resistance C is represented by the smallerportion of the plates, and the contac -rollers attached to the travelingbridge G is the same in function as lever D. The rollers will first outout the whole of the main resistance, and then by their further movementwill cut out a part of the field-magnet coils through a resistanceoffered by the plates at the right-hand end of the box. As seen in Fig.2, the rollers are jonrnaled on the end of short pivoted arms J, helddown in contact with the surface of the plates by a spring L. The arm Jis attached to the under side of the bridge G. By this arrangement thereis no tendency of the guide to bind by reason of the pressure of thesprings downward upon the plates, no matter which direction it may bemoving.

hen the resistance is used in electric-railway service, it will bepreferably placed upon the car-body, and a convenient form of mechanismfor moving the bridge G back and forth over the boxes is seen in Figs. 5and 6. A

lever S, pivoted at s, is connected at one end of the bridge by a pinand slot. Toits other end is pivoted a link T, which is itself pivotedto the lower end of a lever U, journaled to the front end of the carplatform and thrown transversely to one side or another to control theresistance, as desired.

\Vhat I claim as new, and desire to secure by Letters Patent, is

1. The combination, with a resistance composed of a series of metallicplates in contact with one another, of a contact passing over saidplates, consisting of a roller journaled on an arm which is movable on acenter eccentric to the roller.

2. An artificial resistance composed of separate rows or series ofplates in contact arranged in pairs and a contact-maker which connectselectrically the rows of each pair while the pairs themselves arepermanently connected in series, as described.

3. The combination, with an electric motor having a sectional field andan electrical resistance consisting of a number of plates in contactwith one another, of a supplementary resistance in circuit between theterminals of different sections of the field and a common controllingdevice for both the main andsupplementary resistances.

4. The combination, with an electrical resistance consisting of a numberof plates in contact with one another, of a controlling device adaptedto move over the surface of the plates and bring more or less of theminto circuit, and aterminal piece in line with said plates, consistingof slate or other non-combustible insulation adapted to form theterminal of the series and receive the final contact.

5. The combination, in an artificial resistance, of a series of platesin contact with one another, a casing therefor of insulatingnoncombustible material open at the bottom, but having aledge or ledgesfor supporting the plates and a contact device passing over the uppersurface of the plates.

In testimony whereof I have hereto set my hand this 8th day of January,1891.

FRANCIS 0. BLACK \VELL.

Vitnesses:

E. L. RAWSON, G. R. BLonenrr.

